Study Links Malaria in Amazon to Deforestation

Researchers are reporting a direct link between epidemic malaria and deforestation in the Amazon rainforest. They say the new finding has implications for global malaria control.

Curious about a return of epidemic malaria in the Peru Amazon in the 1990's, investigators found there was a connection to uncontrolled deforestation.

During a one-year period, they collected mosquitos at sites with varying levels of deforestation. The locations included untouched areas within the Amazon rainforest and locations that have undergone rapid development and landscape change.

The investigators, led by Jonathan Patz of the University of Wisconsin, found that there were 200 times more of the aggressive form of malaria mosquitos called Anopheles Darlingi in the heavily deforested areas than at pristine rainforest sites.

Patz says there is reason to believe the warmer temperatures in deforested areas attract the darlingi. He says his team is trying to confirm that by studying the temperature, acidity, and plant growth along different water bodies.

"We are trying to sort these things out," said Jonathan Patz. "To figure out, are there ways to predict, and therefore prevent, risky situations that enhance the risk of malaria?"

The findings by Jonathan Patz and his team were published in the January issue of the American Journal of Tropical Medicine and Hygiene.

In the same issue, researcher Edward Walker and colleagues in Western Kenya focused on the malaria-carrying cousin of darlingi in sub-Saharan Africa, anopheles gambiae, which lives and breeds almost exclusively in man-made mud puddles.

"...and so we are conducting studies that examine how people make these small bodies of water, and if we can do something to reverse that process so that there are fewer malaria-carrying mosquitoes around," said Edward Walker.

In the study, researchers mapped a village and used it to identify 104 aquatic habitats for the mosquito larvae, including burrow pits, drainage channels, livestock hoof prints and tire tracks.

A separate survey of the village residents found that many of them did not know much about the mosquito or even that it causes malaria. Others did not want to eliminate the habitats because it was a source of water.

Walker says his research shows it is easy to eliminate disease-carrying mosquitoes, but the problem will keep coming back unless the local population is educated.

He says economic conditions need to improve to put malaria under control.

"Development can proceed," he said. "In fact, it needs to. If you look at the history of malaria worldwide, development ultimately results in malaria going away."

Researchers hope the findings help inform policymakers around the world of the link between uncontrolled deforestation and malaria control, and its implications for disease emergence.